MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2, when a private wiki is configured, provides different error messages for failed login attempts depending on whether the username exists, which allows remote attackers to enumerate account names and conduct brute-force attacks via a series of requests.
The implementation of raw message parameter expansion in MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows HTML mangling attacks.
MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows remote attackers to inject > (greater than) characters via the id attribute of a headline.
The language converter in MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows attackers to replace text inside tags via a rule definition followed by "a lot of junk."
The language converter in MediaWiki before 1.27.4, 1.28.x before 1.28.3, and 1.29.x before 1.29.2 allows attribute injection attacks via glossary rules.
The MWOAuthDataStore::lookup_token function in Extension:OAuth for MediaWiki 1.25.x before 1.25.3, 1.24.x before 1.24.4, and before 1.23.11 does not properly validate the signature when checking the authorization signature, which allows remote registered Consumers to use another Consumer's credentials by leveraging knowledge of the credentials.
ApiParse in MediaWiki before 1.23.15, 1.26.x before 1.26.4, and 1.27.x before 1.27.1 allows remote attackers to bypass intended per-title read restrictions via a parse action to api.php.
MediaWiki before 1.23.15, 1.26.x before 1.26.4, and 1.27.x before 1.27.1, when $wgBlockDisablesLogin is true, might allow remote attackers to obtain sensitive information by leveraging failure to terminate sessions when a user account is blocked.
Cross-site scripting (XSS) vulnerability in the CSS user subpage preview feature in MediaWiki before 1.23.15, 1.26.x before 1.26.4, and 1.27.x before 1.27.1 allows remote attackers to inject arbitrary web script or HTML via the edit box in Special:MyPage/common.css.